pic: 1346 Feb 4 2009

[dtengineering]

Thanks for the kind comment on the drivetrain, Akash... mind you, that is about all there is to comment on, isn't there? I figured it would be good to post a shot because we know that most teams are probably like us and counting on things coming together in a big way in the last couple weeks.

As for drive train maintenance... well... as soon as we get it driving and break something we'll let you know! Actually chain tensioning is pretty easy (we slide a block up and down on the bulkheads), the front two wheels pop out by pulling a single bolt, so that is easy. The rear wheels is a bit tricky to pull what with the key and spacers and all, but we've had it apart and together a few times now and are getting better at it. The toughbox disassembles with just four bolts, and if we need to get serious we just drop the whole module off the side of the robot and work on it at the workbench. The idea, however, is that it should run pretty reliably... the rear wheel is direct drive from the Toughbox using the extra long shaft from AndyMark, supported by a bearing pressed in to the outside piece of 3/8" ply. (We've got a CNC router, so it is easy to machine a ten thou press fit.)

The top and bottom of the drive module are rabbeted and glued in place, with 1" gussets on the outside vertical corners. The two chain tensioners/bulkheads/carrying handles (they have handholds machined in to them) are dadoed in place between the wheels. The drive module has to be pretty sturdy as the bumpers will mount directly on to it using 1/4" bolts backed by fender washers to distribute the load.

The front wheel is raised 1/8 of an inch and the majority of the weight is near or behind the rear axle. We are trying to put our CoG as far back as possible so that the robot pivots about a point as close as possible to the trailer hitch. (Which should, hopefully, prevent us tipping over backwards.)

We've been having enough fun with the woodworking this year that one student insists he wants to build a cabinet to go overtop of the control board. If we come in seriously under weight, we may just go and build a custom tool cabinet to fit in to the unused space at the rear of the robot so that we will always have our wrenches and screwdrivers with us on the playing floor.

Jason

P.S. Rick... you posted while I was writing this... great to have others on Pacific Time... but I had problems with the link... is this the robot? http://www.vexforum.com/gallery/show...imageuser=2091 I assume so... it looks very cool and the 2 speed gearbox could be a big help in this years VEX game. In Courtneay last weekend speed and agility were really important in most matches, but the final, final match came down to a rather inglorious shove-fest.